1. Field of the Invention
The present invention relates to an electromagnetic coupling device, and more particularly to a system for dissipating heat from the inductor drum of such device.
Electromagnetic couplings of the type well known in the art include a rotor which is disposed within a rotatable inductor drum. A coil is energized to generate a magnetic field which electromagnetically couples the rotor and drum so that torque may be transferred therebetween. The passage of this magnetic field through the rotor and inductor drum results in the generation of heat during the transmission of torque partially as a result of "slip" between the rotor and the inductor drum (power in=power out+heat). The dissipation of heat has long been a problem in electromagnetic couplings and many different types of cooling systems have been tried in an effort to more effectively dissipate the generated heat. In general, the heat build up limits the speed ratio of the coupling. Thus, by increasing the heat dissipation of a particular size coupling, the speed ratio for that coupling can be increased.
2. Prior Art
The Jaeschke patent, U.S. Pat. No. 3,996,485, discloses an electromagnetic coupling and a rod cooling system therefor. The Jaeschke patent discloses a rotatable inductor drum in an electromagnetic coupling having a plurality of circumferentially disposed grooves therein. A plurality of rods are disposed contiguous to the grooves and each of the rods has a longitudinal axis parallel to the axis of rotation of the inductor drum. As the inductor drum rotates, the rods affect the flow of a cooling medium, which in the present instance is air, into the grooves to dissipate heat from the inductor drum as the inductor drum rotates. In the embodiment disclosed in the Jaeschke patent, U.S. Pat. No. 3,996,485, it has been found that the cooling rods impart noise vibrations to the air and other fixed portions of the coupling as the rods pass thereby. The movement of the cooling rods in a direction perpendicular to the longitudinal axis of the rods causes repetitive beats of air pressure as the rods come in close proximity with the housing and the air vents in the housing upon rotation of the inductor drum. These repetitive beats of air pressure impart noise vibrations to the air due to the fact that the entire length of each cooling rod comes in close proximity to the housing and the cooling vents therein simultaneously.